The three oldest Gloden boys have been known to zip their remote control cars through the expansive deck of a C-17 transport as their family flies on military Space Available flights. And when they tire of that, they have plenty of room to lie down and work on their coloring books.

Their mom, Army wife Callie Gloden, prefers flying Space-A over regular commercial flights. “It’s fun for the kids,” she says.

Adventure aside, you can’t beat the price of flying Space-A. It’s free on flights within the U.S., just $16.10 when flying from the U.S. to overseas locations and $13 when flying from overseas back to the U.S.

But there are some caveats. There are no reservations, so Space-A is just that: Extra passengers fly when there’s room — after mission-required personnel and cargo are loaded.

No one is guaranteed a flight, so you must have flexibility in your schedule, and you must be patient. And you need a backup plan in case you can’t get to where you want to go, or you can’t get back home.

Conditions vary, too. Cindy Gardner, wife of a Navy retiree, has been on Space-A flights that were so packed with cargo it was hard to move. But she, too, loves the adventure of Space-A, never knowing how she’ll be flying.

For example, she’s enjoyed watching up close the precision of midair refueling while flying Space-A on KC-135 tankers. The types of planes offering Space-A seats run the gamut, including commercial aircraft contracted by the military.

Gloden and her husband, Army Staff Sgt. Casey Gloden, have taken about a dozen Space-A flights, but until now, she hasn’t ventured on one by herself with her five children — ages 4 months and 8, 7, 5 and 2 years.

But she plans to try it this summer to go from home near Fort Carson, Colo., to visit her mother in Florida. Because she is an active-duty spouse and her husband is deployed for more than 365 days, she’s allowed to fly in a fairly high-priority category — Category III — and her chances of getting on a flight are pretty good.

“For us to fly home, it would cost $2,000 to $3,000. We can fly Space-A for free,” she says. The only travel expense will be the cost of a rental car to get to her mother’s house from the as-yet-to-be-determined air terminal in Florida where they land.

“Spouses should take advantage of Space-A and do it,” she says. “Everyone’s scared of it, I think. It’s not scary. It’s really kind of fun.”

“Space-A is a balance between your available time and money,” says Dirk Pepperd, a retired Army sergeant first class who runs the Space-A website www.pepperd.com. The average user on his website is in his or her early 60s, with two retirements, time to spare and some disposable income, he says. His site and others include information about lodging on base, ground transportation to the air terminals and more.

Active-duty members and families receive higher priority for getting onto flights, but they also generally have less flexibility in their leave time.

“If you only have a certain amount of leave, do you want to burn it up sitting in a terminal?” Pepperd says. Interviews with active-duty families living overseas reveal they often don’t fly Space-A for that very reason.

Working the system

“It’s hard if you have a certain destination where you want to go,” Gloden says. But if you’re flexible, you have options. When her husband is home, if they decide to fly Space-A, they go wherever they can get a flight because his leave time is limited. Callie Gloden’s schedule is more flexible.

Amid the current budget squeeze affecting many aspects of Defense Department operations, some travelers interviewed said they’re seeing fewer flights available, and in some cases, fewer seats on flights.

However, Air Force Air Mobility Command officials “have not seen a major difference in number of seats from last year to this year,” says Steve Mura of the AMC logistics directorate for travel and policy.

“In regards to sequestration, AMC has not seen any change or impact to Space-A travel, nor have any units reported any decrease in the availability of seats,” Mura says.

Still, travelers should do their research before flying Space-A, says Ann Crawford, publisher of Military Living Publications.

Air Mobility Command “is doing a great job of informing people about Space-A,” she says. She recommends AMC’s website, www.amc.af.mil/amctravel, and notes that many of the air terminals have Facebook pages with flight schedules posted.

According to the Government Accountability Office, in 2011, nearly 200,000 passengers flew Space-A — a program started in 1907 to give active-duty members a break from the “rigors of duty,” GAO said.

Bill Ware, a retired Air National Guard lieutenant colonel, says the system has gotten more user-friendly in the past 15 or 20 years. He volunteers his time helping Space-A passengers at the Air National Guard air terminal in Jackson, Miss.

Each base maintains a register, he says, and once you sign up at that base, you stay on that register for 60 days or until you fly out. This allows you to sign up before you plan to travel.

The terminals’ registers list passengers organized by priority category and the date and time they signed up for travel. The longer you’ve been signed up, the further you move up the list within your category.

You can sign up in person at the terminal or remotely by email, fax or regular mail. The email or fax data header establishes the date and time of sign-up. Travelers can call the terminals to find out where they stand on the register. Active-duty personnel must make sure their fax or email is sent no earlier than the effective date of their leave.

You can sign up at the AMC website and through www.takeahop.com. At that commercial site, run by a military retiree, you can download an app for your personal computer or mobile device for $3.99 that allows you to sign up at multiple locations and get information on different bases.

On the day you want to travel, you must mark yourself present for travel either at the kiosk at the terminal or by informing a passenger service agent at the counter.

Ware advises those who register by email to take a copy of their sent email to the terminal. “Go to the counter to make sure you’re registered. If not, show them the email, and they will back-date your sign-up.”

He advises planning the sign-up dates before your vacation so you’ll have as much time as possible to move up in priority. That includes the return trip. For example, if you’re going to be in Ramstein, Germany, for three weeks, sign up for the return trip to the U.S. before you go.

Ware also advises calling the terminal a day or two before you plan to leave. Once, when he planned to leave Germany the following Friday, he called on Wednesday to check on flights.

They told him to be there Thursday if he wanted to get a flight in the next several days. “Conversely, if they had said there were no flights for a week, we could have toured longer,” he says.

Backup plan

Gardner has been flying Space-A with her husband, retired Navy Reserve Lt. Cmdr. John Gardner, for the past 18 years, and says getting there is sometimes the best part of the journey.

The most important consideration, she says, is to have a backup plan. At times, the family has had to buy commercial airline tickets to get home.

“One of our favorite trips was a mystery trip. We packed our bags, went to Travis Air Force Base [California] and said we’d take the first plane available. We flew to Charleston for a wonderful trip. We gave ourselves a week to get back, but we couldn’t get a flight.”

One Navy wife said four of her friends in Singapore flew Space-A recently and all had to fly at least one leg of their journey by commercial flight.

“If you get stuck for a week without a flight, you have to consider the costs of getting back and forth to the terminal, and for the hotel,” Pepperd says.

He advises retirees not to travel during the summer or around the holidays, when more active-duty families tend to be on the go, especially from overseas.

In 2009, the Gardners planned to catch a flight from Travis to meet their son and his wife in Hawaii for Christmas. “We never got there,” Cindy Gardner says.

They had signed up for a flight well in advance, she said, “but there weren’t many planes flying that year, and there were many, many families. It’s so cyclical. You can never predict.”

Sometimes it's just plain luck

Research into flight schedules, early sign-ups and other planning can make the experience run as smoothly as possible. But luck plays a part, too.

In 2010, the Gardners arranged to meet up with friends in Europe for a vacation. “We went to Travis [Air Force Base] with low expectations and figured we’d need a week” to get a flight to Europe, Cindy Gardner says.

“But when we got there, they made an announcement that a plane was going to Mildenhall [in England] an hour later. We got on the plane, got to Europe a week early, and had a wonderful time. We’d never been to England,” she says.

She and her husband have made lifelong friends while flying Space-A. “These are the most wonderful military families you could expect to meet in the world,” she says.

But before the adventures and good times of Space-A, she says, “You must have flexibility and patience. If you don’t have it, don’t even try flying Space-A.”